1. Field of the Invention
This invention relates to spin axis stabilization of a spinning orbital body and, more particularly, to a method of stabilizing a spinning orbiting body without resort to active stabilizing mechanisms.
2. Description of Related Art
In previously known methods of attempting to stabilize the orientation of a spinning orbital body, such as a satellite, various active means are generally employed. The most common of these means is the use of thrusters using some form of mass expulsion to produce attitude control moments which interact with the subject body mass and geometry to produce the desired precession of the spin axis of the body to maintain a stable attitude orientation.
Another stabilization method found in the prior art is the use of electrical energy or magnetic fields to produce magnetic moments which react with the earth's magnetic field to produce control torques for precessing the spin axis of the orbital body.
Thus, to create and maintain the desired control torque moments, these known prior art methods require additional complexity, weight and energy consumption that lessen the useful payload and efficiency of the orbiting body for its designed mission.
While these known prior art methods are acceptable for relatively short-lived orbital bodies and missions, where the necessary trade-off of weight, complexity and energy consumption may be feasible, the present goals of establishing a permanent orbiting body, such as an earth orbiting space station, present unique demands on payload weights and overall system efficiency requiring new stabilization methods and systems that will result in greater reliability and dependability of operation at reduced levels of weight, complexity and energy consumption.
Accordingly, each of these previously known methods has a number of disadvantages which are overcome in the practice of the present invention. Specifically, the desired orientation of the body may be produced without the use of thrusters or mass expulsion, thus eliminating the need to carry attitude control fuel or propellant on the orbiting body. The desired orientation of the body may also be produced without the expenditure of electrical energy or the development of magnetic fields of any kind, thus greatly reducing the energy requirements of the orbiting body. The desired orientation of the body may be produced without the need for attitude sensing devices to produce control system error signals, thus providing for reduced cost and improved reliability. Finally, as a result of the system design and configuration embodied in the method of this invention, the desired attitude of the spinning body may be passively maintained, and the maximum excursion of the sun angle from the equatorial plane of the spinning body may be kept suitably small for solar array efficiency.